The present invention relates to a novel saccharide, a process to produce the same and also its uses, more particularly, to a non-reducing oligosaccharide as represented by the formula .beta.-D-oligoglucosyl .alpha.-D-glucoside, .alpha.-D-oligoglucosyl .beta.-D-glucoside or .beta.-D-oligoglucosyl .alpha.-D-oligoglucoside and a process to produce the same, as well as to its uses. 2. Description of the Prior Art
There have been known several types of non-reducing oligosaccharides: a type where as found in sucrose, erlose, raffinose, melezitose and kestose, Glucose and fructose are bound via the .alpha.-1 and .beta.-2 linkages, in other words, oligosaccharides having a sucrose structure in the molecules; sugar alcohols such as maltitol, maltotriitol and lactitol; and neotrehalose where glucose is bound each other via the .alpha.-1 and .beta.-1 linkages. Oligosaccharides having a sucrose structure in the molecules are, however, less stable et the .alpha.-1 and .beta.-2 linkages and readily decomposable in an acidic solution. Such less stability provides several restrictions in the processing of foods and the like. Sugar alcohols, which are usually prepared by hydrogenation at an elevated pressure, are excellent in stability, however, less digestible and assimilable in human body so that they have the drawback that when excessively taken they may induce diarrhea. While neotrehalose (.alpha., .beta.-trehalose) is stable and handles readily, and has a gentle and mild sweetness. As disclosed in Japan Patent Kokai No.176,490/92 or No.252,973/93 by this applicant, neotrehalose is orally or parenterally administered to human bodies and well metabolized and advantageously utilized as an energy source without toxicity and side effects. Furthermore, since neotrehalose is not readily fermentable by dental-carries-inducing microorganisms, it can be utilized as a less cariogenic sweetener. These superb properties are found in neotrehalose, however, for the sake of viscosity-imparting ability and moisture-retaining ability, the development of a higher molecular oligosaccharide exhibiting the properties of neotrehalose is expected.